Amirkabir University of Technology Amirkabir Journal of Mechanical Engineering 2008-6032 52 10 2019 04 23 e Limit Forming on Density Dislocation of Effect T e Limit Forming on Density Dislocation of Effect T 2709 2724 3376 10.22060/mej.2019.15728.6189 FA Sedigheh Mohamadnejad Phd student,Faculty of mechanical engineering university of Guilan, rasht ,iran Ali Basti Reza Ansari Faculty of mechanical engineering /University of Guilan/rasht /Iran Journal Article 2019 01 29 One of the most important and widely used tools to predict the behavior of sheets is   the forming limit diagram. The Marciniak-Kuczynski model is one of the prediction methods, which can be combined with the phenomenological or the crystal plasticity equations to achieve the desired results. In this research, to predict the forming limit diagram, the direct combination of the Marciniak- Kuczynski method with the crystal plasticity has been applied. The direct method is chosen due to the particular state of the mathematical equations associated with forming limit diagram. In this study a face-centered cubic polycrystalline metal has been used here, so, the Taylor method for the polycrystals can be used. Although this method ignores the interactions between the crystals to describe plasticity, it can also reduce the computational cost by simplifying the strain uniformity theory. In this study, polycrystal plasticity and dislocation methods have been merged in a new way. Only the hardening process is modeled based on the dislocation density and its modifications, and the entire analysis is based on the rate-dependent crystal plasticity. For the first time, the forming limit diagram is plotted to take into account the effect of dislocation density, and the results show that considering the effect of the dislocation density on the shear strength changes, the forming limit diagram formulation becomes nearer to the experimental values. One of the most important and widely used tools to predict the behavior of sheets is   the forming limit diagram. The Marciniak-Kuczynski model is one of the prediction methods, which can be combined with the phenomenological or the crystal plasticity equations to achieve the desired results. In this research, to predict the forming limit diagram, the direct combination of the Marciniak- Kuczynski method with the crystal plasticity has been applied. The direct method is chosen due to the particular state of the mathematical equations associated with forming limit diagram. In this study a face-centered cubic polycrystalline metal has been used here, so, the Taylor method for the polycrystals can be used. Although this method ignores the interactions between the crystals to describe plasticity, it can also reduce the computational cost by simplifying the strain uniformity theory. In this study, polycrystal plasticity and dislocation methods have been merged in a new way. Only the hardening process is modeled based on the dislocation density and its modifications, and the entire analysis is based on the rate-dependent crystal plasticity. For the first time, the forming limit diagram is plotted to take into account the effect of dislocation density, and the results show that considering the effect of the dislocation density on the shear strength changes, the forming limit diagram formulation becomes nearer to the experimental values. https://mej.aut.ac.ir/article_3376_14e422f05b68cc0139988e128ee880df.pdf